In the current Japanese and European side impact regulation, occupant protection is evaluated based on anthropomorphic test device (hereafter referred to as the more commonly used term “dummy”) measurements recorded in a stationary car impacted by a moving deformable barrier (MDB). In order to validate and improve the side impact test procedures of the regulation and the associated new car assessment program, it is necessary to compare the side impact test procedure with car-to-car side impact tests conducted in various conditions. In this research, a series of car-to-car side impact tests using a small sedan as the target vehicle was conducted as follows: (1) A striking car impacted against the stationary car at 50 km/h at an impact angle of 90 degrees. (2) A 1BOX vehicle impacted the stationary car at 50 km/h at an impact angle of 90 degrees. (3) Both cars were moving, and the striking car impacted the struck car at an impact angle of 90 degrees. The ratio of the striking car to struck car velocity was 2:1 (48 km/h vs. 24 km/h). The car deformation and dummy injury measures were compared. In comparing the results for the condition that both cars were moving versus that the struck car was stationary, it was observed that the deformation and the dummy injury measures were smaller when both cars were moving. Therefore, it was probable that a test in which the struck car is stationary could be a more severe condition than that in which the struck car is moving. When comparing the results that striking vehicle was either a sedan or a 1BOX, the chest deflection was larger when striking car was the 1BOX. According to the structure of the 1BOX, the deformation of the struck car was larger. Consequently, it was demonstrated that the front structure of the striking vehicle could affect the deformation and the dummy injury measures of the struck car.